1. Field of the Invention
The present invention relates to an optical pickup device, and more particularly, to an optical pickup device having a heat radiation structure.
2. Description of the Related Art
Generally, disk drives, such as compact disk players (CDPS) or digital versatile disk players (DVDPs), use an optical pickup device to record and/or reproduce information on/from a disk by moving along a radius direction of the disk, irradiating a light beam on the disk, and receiving a light beam reflected from the disk. The optical pickup device, as shown in FIG. 1, includes a base 17 in which an optical system (not shown) is built, a blade 12 which is movably supported by a plurality of wires 16 having first ends which are fixed to a holder 13 on the base 17 and second ends which are fixed to the blade 12, an objective lens 11 mounted in the blade 12, focusing coils 14 and tracking coils 15 which are installed on the blade 12 and form an electrical path to move the objective lens 11 along a focusing direction A and a tracking direction B, magnets 19 which generate an electromagnetic force due to currents flowing through the focusing coils 14 and the tracking coils 15 (elements 14 and 15 also being referred to as driving coils) to drive the blade 12, and yokes 18a and 18b. Thus, if the recording and reproduction job of the information begins to be processed, the light beam emitted from the optical system is focused by the objective lens 11 and is irradiated on a recording surface of a disk (not shown). At this time, a current to control a position of the objective lens 11 to focus the light beam is supplied to the driving coils 14 and 15 in order to irradiate the light beam onto a correct position of the recording surface, thereby driving the blade 12.
However, when the above optical pickup device is operated, heat of about 70–80° C. is generated in the focusing coils 14 and the tracking coils 15. If the heat thus generated is not well radiated, the heat is transferred to the blade 12 and the objective lens 11, etc., and as a result, heat distortion of the objective lens 11 or the rigidity reduction of the blade 12 is generated. This could severely affect reproducing capacity of the optical pickup device. As a first measure for solving the above problem, the optical pickup device shown in FIG. 1 has a heat radiating wrinkle on a cover 10 to enlarge a surface area to radiate heat. However, since the cover 10 provided with the heat radiating wrinkle directly contacts only the base 17 and does not contact the blade 12 and the driving coils 14 and 15, the heat generated from the driving coils 14 and 15 is transferred to the cover 10 by only air. Although the heat radiating area of the cover 10 is enlarged, the heat radiation efficiency of the heat generated from the driving coils 14 and 15 decreases, and therefore, it is very difficult to prevent the heat from being transferred to the objective lens 11.
As a second measure, a separate heat radiating fan is installed in the optical pickup device to cool the heat generated from the coils. However, since a heat sensor to sense overheating, the heat radiating fan to generate a wind (air flow), and a motor must be installed separately in the optical pickup device, the structure of the optical pickup device is complicated while the size thereof is large. That is, the optical pickup device which must have the separate heat radiating fan and the motor, etc., has a great drawback on a design while the recent trend demands a small-sized and light-weight disk driver. Particularly, in a case of adopting the optical pickup device to portable devices such as a notebook computer, the separate motor is a direct component that leads to fast battery consumption of the portable device.
As a third measure, as shown in FIG. 2, a heat radiating member 23 is adhered to a blade 21 provided with an objective lens 20 and coils 22 so that heat generated in the coils 22 is easily radiated by the heat radiating member 23. While the radiation efficiency is slightly increased in the heat radiation structure proposed above, the heat generated in the coils 22 cannot be prevented from being directly transferred to the objective lens 20. That is, since only part of the heat which has been already transferred to the objective lens 20 through the blade 21 is radiated by the heat radiating member 23, the heat radiating member 23 slightly contributes to suppress the heat distortion of the objective lens 20.